The phrase "to protect the back" means to keep someone or something safe from harm or danger. It can also mean to provide support or assistance to prevent negative consequences. Full definition
Dual hook - and - loop straps provide adequate foot and ankle support, while heel bumpers protect the back of the foot from injury during play. (thetoddle.com)
Below you will find a super simple routine to help protect your back from pain. (health.com)
He is just back from injury but i felt he was quite bad in protecting the back four. (justarsenal.com)